Professor Gillian Triggs, president of the Australian Human Rights Commission, has said there is a "widening gulf" between the constitutional powers of the Australian Government and international law when it comes to the welfare of refugee children.

Speaking today at the launch of a report into the welfare of children held at the Wickham Point detention facility in Darwin, Professor Triggs said that while the commission respected yesterday's High Court decision confirming the constitutional right of the Australian Government to offshore detention of asylum seekers, the decision did not deal with international law or international treaties.

"Sadly, there is a widening gulf between the constitutional powers of the Australian Government and the country's international legal responsibilities. Our national laws, in effect, allow us to wash our hands of the welfare of refugee children once they leave Australia's shores."

- Professor Gillian Triggs, president of the Australian Human Rights Commission

"Sadly, there is a widening gulf between the constitutional powers of the Australian Government and the country's international legal responsibilities," she said.

"Our national laws, in effect, allow us to wash our hands of the welfare of refugee children once they leave Australia's shores. Our laws impose no standards on Nauru to meet educational and medical needs of refugees. Indeed, the government’s chilling defence to claims that it is in breach of its duty of care is that it has no control over the treatment of refugees transferred to Nauru."

Professor Triggs says the government defence that Australia's policies of mandatory detention and offshore processing are necessary to stop the boats and save lives are a "profoundly misleading conflation of the two issues".

"There is little evidence that detaining children for prolonged periods is an effective deterrent to people smugglers. Indeed, both former Ministers of Immigration Scott Morrison and Chris Bowen, have confirmed this under oath to the AHRC Inquiry 18 months ago."

Urging the Australian Government to "take the mature and human decision to temper its techinical legal powers", Professor Triggs said it now rested with the "international community to use its influence to ensure the safety of refugee children under the agreed principles of international law". She said she also hoped that the "open-hearted Australian people can persuade both the Coalition and Labour parties to return to the ideals of our democracy by allowing the children and families to remain in Australia to rebuild their lives as healthy and fruitful citizens".

The comments come after the High Court on Wednesday handed down a 6-1 decision, rejecting a constitutional challenge to the Federal Government's policy of offshore asylum seeker processing. The decision directly impacts more than 250 asylum seekers, including 36 babies born in Australia, who the government has indicated will now be deported to Nauru. The asylum seekers had been transferred to Australia for medical assistance.

Meanwhile, paediatrician Professor Elizabeth Elliott - who visited the Wickham Point detention facility in October along with fellow paediatrician Dr Hasantha Gunasekera and AHRC staff, said children they encountered there, most of whom had spent months on Nauru, were "among the most traumatised we have ever seen in our 50 years of combined professional experience".

"Many of the children had palpable anticipatory trauma at mention of return to Nauru," Professor Elliott said. "Nauru is a totally inappropriate place for asylum seeking children to live, either in the detention centre or in the community."

Dr Gunasekera added that the only appropriate solution was to "remove the children from the environment that is causing or exacerbating their mental health".

The latest report comes in the wake of The Forgotten Children report issued more than a year ago which found that 34 per cent of children in detention, whether on or offshore, had severe to moderate mental illness compared with just two per cent in the broad Australian community.

The AHRC said Australia continues to detain about 80 children, including the 36 babies, at Wickham Point and about 70 in the regional processing centre on Nauru.

Meanwhile, The Australian reports that the Anglican Dean of Brisbane, Peter Catt, yesterday declared St John's Cathedral in Brisbane a "sanctuary" for those facing removal to Nauru. Rev Dr Catt, who is also the chairperson of the Australian Churches' Refugee Taskforce, told newspaper the High Court ruling on the offshore processing policy "fundamentally goes against our faith, so our church community is compelled to act, despite the possibility of individual penalty against us".

He said the "extraordinary step" would attract the attention of church communities around the world and that while there might not be a legal basis for the Old Testament concept of sanctuary, he was prepared for the "appalling spectacle" of authorities raiding the cathedral to remove asylum seekers.

The church is the latest in a number across the country which have similarly declared they would provide a sanctuary to asylum seekers. According to The Australian, they include St George's Anglican Cathedral, St Cuthbert's Anglican Church and Wesley Uniting Church in Perth, the Pitt Street Uniting Church, Gosford Anglican Church and the Wayside Chapel in New South Wales, the Pilgrim Uniting Church in Adelaide, St David's Anglican Cathedral in Hobart and Christchurch Anglican Cathedral in Darwin.

It is understood the legal power of sanctuary has not been tested under Australian law.

Earlier, Paul Power, CEO of the Refugee Council of Australia, said the High Court decision did not "compel" the Australian Government to send the "innocent and vulnerable" people back to Nauru.

'We urge the government to consider the best interests of these children, and their families and do everything in their power to ensure their safety and protection, by keeping them in Australia," he said in a statement released after the decision was handed down on Wednesday.

Immigration Minister Peter Dutton said transfers back to Nauru would be made on a case-by-case basis and the "exceptional circumstances" would be looked at. "We are not going to put children in harm's way," he told the ABC.

Mr Dutton said the Australian Government had to be compassionate but realistic in its actions following the decision on Wednesday and did not want to encourage anything that would lead to more people drowning in attempts to reach Australia.

"We are going to continue our vigilance against people smugglers, while providing compassion to those who have been traded in this evil, people smuggling organised criminal syndicate," he said.

"We are acting in the best interests, not only of these children, but children that would follow them. I don't want to reopen the open border policy."